Dental pulp is a soft bonding tissue located in the center of the tooth. Various harmful stimuli may cause inflammation and pathological changes in the dental pulp. Inflammation can have an acute or a chronic course depending on the type and strength of the harmful stimulus and on the defense forces of the organism. The acute inflammatory reaction is characterized by redness and heat due to increased blood flow, swelling due to increased blood vessel permeability, and pain due to increased volume that presses nerve endings and releasing inflammatory mediators. In chronic inflammation, cellular response and cell proliferation dominate, pain is usually minimal or nonexistent. Pathological changes of the dental pulp are divided according to pathohistological and clinical classification. The pathohistological classification is divided into: hyperemia, acute and chronic pulpitis, necrosis and gangrene. The clinical classification, on the other hand, is divided into: reversible and irreversible pulpitis, internal resorption and necrosis. In clinical practice, it is important to know the difference between reversible and irreversible pathological changes because it is sometimes possible, by our preventive procedure, to prevent inflammation from becoming an irreversible form. Other changes that can be found in the pulp are calcifications. They can be found in the form of diffuse calcifications or pulp stones.